The present invention relates to a drill and a cutting insert therefore. The drill comprises a shank, a portion provided with lands and chip flutes, at least one cutting insert site in its axially forward end, provided with a hole, at least one cutting insert, provided with a hole, and tightening means, arranged to to be received by the holes in order to hold the cutting insert in a cutting insert site. The drill has a direction of rotation relative to a work piece and has a center axis. The cutting insert has a cutting edge along the line of intersection of a chip surface and a clearance surface of the cutting insert, the clearance surface being arranged behind the cutting edge in the direction of rotation of the drill. The cutting edge extends from the vicinity of the center axis of the drill towards the periphery of the drill. The cutting insert has a lower side opposite to the clearance surface.
A drill is shown in EP-A2-0 172 148 wherein the hole of the cutting insert terminates in the chip surface of the cutting insert. This means that the insert must be relatively large to be able to accomodate the hole, which negatively influences the strenth of the drill body, when the drill body has a small diameter. Furthermore the known drill is sensitive to tolerance faults.
An object of the present invention is to provide a drill having easily exchangeable cutting inserts.
Another object of the present invention is to provide cutting inserts for the drill that demand little hard material to be produced.
Still another object of the present invention is to provide a drill whose cutting inserts are rigidly fixed to the drill body.
Still another object of the present invention is to provide a drill whose cutting inserts can be covered by wear resistent layers.
Still another object of the present invention is to provide a drill whose cutting inserts can consist of a very hard material.
Still another object of the present invention is to provide a drill being relative unsensitive to tolerance faults.